Process for reducing pilling tendencies of acrylic fibers and fiber products thereof

ABSTRACT

Acrylic fibers, or products therefrom, are reduced in pilling tendencies when treated under specific conditions with an aqueous solution of an alkylsulfate salt and sodium carbonate.

United States Patent Sasada Aug. 19, 1975 [54] PROCESS FOR ED IN FILLING2,130,460 9/1938 Evans 6: a1. 19 66 TENDENCIES OF ACRYLIC FIBERS AND 5:22; :32 i 3 32 6 6 omas e a FIBER PRODUCTS THEREOF 2,689,195 9 1954Martone 117 65 [75] Inventor: Juichi Sasada, Okayama, Japan 2,998,2968/1961 Hennemann... 18/1155 3,127,305 3 1964 Hirshfeld 161/64 1Asslgneei Amman cyanamld Company, 3,152,919 10 1964 Biles et a1.117/138.8 Stamford, Conn- 3,264,705 8/1966 Kovarik 28/76 [22] Filed:Dec. 13, 1973 FOREIGN PATENTS OR APPLICATIONS [21] Appl. N0.: 424,4081,030,317 5/1966 United Kingdom I Primarv Examin'erP. E. Willis Jr. 52US. Cl. 427/390 A A I J L 511 Im. c1. B44d l/06; D06m 13/26 gen [58]Field of Search 8/115.6; 19/66 R; 28/75 R,

28/74 H; 1l7/138.8 UA, 139.5 CF, 139.5 [57] ABSTRACT CQ; 252/8] 550Acrylic fibers, qr products therefrom, are reduced in pilling tendencieswhen treated under specific c0ndi- [56] Refere e Cited tions with anaqueous solution of an alkylsulfate salt UNITED STATES PATENTS and Sodmmbw 2,012,610 s/1935 Lenher 28/1 181C1aims, No Drawings PROCESS FORREDUCING PILLING TENDENCIES OF ACRYLIC FIBERS AND FIBER PRODUCTS THEREOFThis invention relates to a process for reducing the tendency of acrylicfiber product to pill. More particularly, the present invention relates.to such a process where by treating the acrylic fiber with an aqueoussolution containing an alkyl sulfate and sodium carbonate, the pillingtendencies of the fiber products are permanently reduced.

It is well known that acrylic fibers and products therefrom are popularfor such uses as jerseys, sweaters, dress shirts, knitting yarns and thelike because they possess outstanding properties such as vivid dyedcolors, unusual bulk, and others not found in other synthetic fibers.

However, acrylic fibers, in spite of their great usefulness, are notfree from deficiencies and processes by which these deficiencies can beovercome are urgently sought.

A particular deficiency of the acrylic fibers is their tendency to pill,i.e., to form a small rounded mass of fiber. Pilling lowers theaesthetic appeaarance of appearance fiber products and, therefore, thereis a great need to provide a successful process for overcoming thepilling tendencies of acrylic fibers and products therefrom.

Pilling, however, is not a problem peculiar to acrylic fibers but is adeficiency common to products of most other synthetic fibers such aspolyamide, polyester, etc. The formation of pills takes place on thesurface of woven and knit fabrics by repeated friction of the fiberswith themselves during normal wearing of the fiber products. Woven andknit fabrics of synthetic fibers appear to have a greater tendency topill in use than do fabrics of natural or regenerated fibers such ascotton and rayon and a prolonged wearing period will impair theaesthetic appearance and wearing comfort of the fiber products. Forthese reasons, an urgent need in overcoming the pilling problem arises.

Pilling is also observed in the case of fiber products of natural andregenerated fibers. However, in the case of such fibers, because oftheir low strength, the pills generated will fall off the fiber productby simple mechanical friction during wearing or washing. As a result,there will be little accumulation of pills during the service use of theproducts of natural or regenerated fibers. On the other hand, becausesynthetic fibers, e.g., acrylic fibers, have much greater strength thannatural or synthetic fibers, the rate at which pills form is greaterthan the rate at which they fall off fiber products. Accordingly, thepills formed remain semipermanently on the fabric surface without beingremoved by friction forces and their presence greatly impairs aestheticappearance and wearing comfort.

Previous methods considered for overcoming the pilling problem include,for example: the selection of fibers of the greatest possible lengthvand fineness; the use of fibers of non-circular cross-section, e. g.,triangular cross section; the use in preparing woven and knit fabrics oftightly twisted two-ply yarns; the avoidance of high percentages of highstrength fibers in fiber blends; as well as others. However, each of theproposed methods is accompanied by deficiencies inpractical use, such asrestriction of particularfiber materials, impairment in strength,texture, bulk, and the like properties of the fiber product. Suchrestrictions also severely limit practical use of synthetic fibers.

Other methods considered are those of chemical treatment of the acrylicfibers. However, none of the suggested chemical treatments was able toavoid fiber discoloration or texture impairment;

As can be readily appreciated, the solution to the problem of pilling ofsynthetic fibers, including acrylic fibers, has not yet developed to apractical level. Accordingly, an urgent need in the art would befulfilled if a practical process for reducing the pilling tendencies ofacrylic fibers could be provided.

In accordance with the present invention, there is provided a processfor reducing the pilling tendencies of acrylic fibers and fiber productsthereof which comprises treating an acrylic fiber or product thereofobtained from an acrylonitrile polymer containing at least weightpercent acrylonitrile and any balance of one or more ethylenicallyunsaturated monomers copolymerizable therewith with an aqueous solutioncontaining a salt of an alkyl sulfate of. 8 to 16 carbonatoms, said saltselected from those of sodium, potassium, and ammonium salts, and sodiumcarbonate, said treatment being carried out at a temperature in therange of about 60 to C. and so as to deposit from about 0.1 to 2.0weight percent of said alkyl sulfate and from about 0.5 to 3.0 weightpercent of sodium carbonate, both percentages based on the dry weight ofsaid fiber or fiber product, and thereafter drying the treated fabric ata temperature in the range of about 60 to l20C.

In carrying out the process of the present invention, an aqueoussolution of alkyl sulfate salt and sodium carbonate is prepared andheated to the proper temperature, the acrylic fiber or fiber product isentered into said solution so as to be impregnated "thereby, the amountof impregnant on the fiber or fiber product is adjusted to the properweight pick-ups of treating agents, and the thus-treated fiber 'or fiberproduct is then dried at a temperature in the range of about 60 tol20C., whereupon the anti-pilling character is durably imparted.

The term alkylsulfate, as employed herein, is intended to mean amonoalkyl ester of sulfuric acid which is in the form of the sodium,potassium, or ammonium salt. The alkyl group will have from about 8 tol6 carbon atoms in straight or branched chain. A particularly usefulalkylsulfate is sodium laurylsulfate because of its availability andcost.

Although the alkylsulfate may impart some improvement in anti-pillingcharacteristics when used without sodium carbonate, the combinationprovides markedly superior characteristics.

In Table I, which follows, is shown the relationship betweenanti-pilling effectiveness and the concentrations of alkylsulfate andsodium carbonate.

TABLE l-Continued Concentrations in weight percent Based on the weightof dry fiber From the data of Table l and additional studies, theeffective use levels for obtaining improvement in pilling tendencies ofacrylic fibers and products thereof is found to lie in the range ofabout 0.1 and 2.0 weight percent of alkylsulfate and about 0.5 to 3.0weight percent of sodium carbonate, both percentages being based on thedry weight of fiber. Preferably, the uses will be about 0.1 to 1.0weight percent of alkylsulfate and 0.5 to 2.0 weight percent of sodiumcarbonate based on the dry weight of the fiber.

-The effect of the temperature of fiber treatment on the pillingtendencies thereof using 0.5 weight percent of alkylsulfate and 2.0weight percent of sodium carbonate is shown in Table II, which follows.

TABLE ll Treating Temperature (C.) Pilling Tendency 20 Moderate toSlight 40 Slight 60 None 80 None TABLE III Drying Temperature (C.)Pilling Tendency 60 Slight to None 80 None 100 Slight to None I20 Slightto None From the data in Table III and additional studies, the effectivedrying temperature is in the range of about 60 to 120C, preferably about80C.

In treating acrylic fiber or fiber product therefrom, an aqueoussolution containing both alkylsulfate and sodium carbonate isconveniently prepared and the solution heated to an effective treatingtemperature. The fiber or fiber product is treated so that the properamount of treating agents are present on the fiber. Adequate pickups canbe controlled by the concentration of agents in the treating solutionand time of treatment. Excessive pickup may be reduced by appropriatemechanical procedure, i.e., centrifugation, padding, and the like.Neither of the agents is normally substantive to the fiber.

The term acrylic fiber" as used herein, is intended to mean an acrylicfiber obtained from an acrylonitrile polymer containing at least about80 mol percent of acrylonitrile and any balance of one or moreethylenieally unsaturated monomers copolymerizable therewith.

Suitable comonomers include for example an acrylic acid ester, :1methacrylic acid ester, acrylamide, methacrylamide, N-substitutedacrylamides and methacrylamides, vinyl acetate, vinylpyridine,allylsulfonic acid, methallylsulfonic acid, and the like.

The expression fiber product, as used herein, is intended to meanfibrous constructions containing at least about 50 weight percent of thedefined acrylic fiber based on the total product weight. Thus, theproduct may consist solely of the acrylic fiber or may be a blendthereof with natural fibers such as cotton or wool. The construction maybe in the form of fiber, yarn, woven or knit fabric, non-woven fabric,and the like.

wherein the treating agents are combined firmly and deeply penetrated sothat the coefficient of friction between fibers is increased, theindividual fibers do not become disengaged from one another, and anypills formed freely fall from the fibrous bulk thereby remarkablyimproving the anti-pilling tendencies of the material treated. inaddition, the anti-pilling improvement is highly durable and is notaccompanied by any adverse effects on other fiber properties.

The invention is more fully illustrated by the examples which follow,wherein all parts and percentages are by weight unless otherwisedesignated.

The method of measuring the pilling tendencies is as follows.

The test specimens, are measured using a conventional pilling tester. Afabric in the form of a swatch about 10 X 12 centimeters is wrappedaround an appropriate rubber tube, 2.5 centimeter in diameter and 15centimeter in length. The edges are sown together so as not to overlapone another and the ends are secured to EXAMPLE 1 A jersey clothcomposed of 100% acrylic fiber which was yarn-dyed was treated for 10minutes in an aqueous solution containing 0.5% sodium laurylsulfate and2.0% sodium carbonate. The acrylic fiber was spun from a polymercontaining 89 mole percent acrylonitrile and ii mole percent methylacrylate. The treatment was carried out at 60C. The treated fabric wascentrifuged to adjust the pickup of the fabric to 100%. The fabric wasthen dried at C. for 30 minutes. The dried fabric was then rinsed withwater at room temperature for 5 minutes and allowed to dry atatmospheric conditions.

For comparison purposes, an untreated sample of the same fabric wasemployed. In addition, two additional comparisons were made, one(Comparative Example A) in which the treating solution contained 0.5%sodium laurylsulfate alone and another (Comparative Example B) in whichthe treating solution contained 2.0% sodium carbonate alone, thetreatments following the procedure above.

The various fabrics were evaluated for pilling tendencies initially andafter washing. Washing was with 2 grams per liter of detergent at 40C.for 10 minutes using a 50:1 l'q uorzfabric ratio. followed by rinsingand The present process provides fiber or fiber products I drying usingdomestic washing and drying equipment. Results are given in Table IV.

TABLE IV Pilling Tendency Sample lnitial After Washing Example 1 NoneNone Comp. Ex. A Slight Moderate Comp. Ex. B Moderate ConsiderableConsiderable Considerable Untreated to Extensive to Extensive EXAMPLE 2TABLE V Sample Filling Tendency Example 2 Slight to None UntreatedModerate I claim:

1. A process for reducing the pilling tendencies of acrylic fibers andfiber products thereof which comprises treating an acrylic fiber orproduct thereof obtained from an acrylonitrile polymer containing atleast weight percent acrylonitrile and any balance of one or moreethylenically unsaturated monomers copolymerizable therewith with anaqueous solution containing a salt of an 'alkylsulfate of 8 to 16 carbonatoms, said salt selected from sodium, potassium, and ammonium salts,and sodium carbonate, said treatment being carried out at-ayt'emperaturein the range of about 50 to C. and so as to deposit from about 0.1 to2.0 weight percent of said alkylsulfate and from about 0.5 to 3.0 weightpercent of sodium carbonate, both percentages based on the dry weight ofsaid fiber or fiber product, and thereafter drying the treated fabric ata temperature in the range of about 60 to l20C.

2. The process of claim 1 wherein the alkyl sulfate is sodiumlaurylsulfate.

3. The process of claim 1 wherein the alkylsulfate is deposited on saidfiber or fiber product at 0.1 to 1.0 weight percent,

4. The process of claim 1 wherein the sodium carbonate is deposited onsaid fiber or fiber product at 0.5 to 2.0 weight percent.

5. The process of claim 1 wherein the treated fabric is dried at 80C.

6. The process of claim 1 wherein the fiber or fiber product is treatedat 60 to 80C.

7. The process of claim 1 wherein the fiber is in yarn form.

8. The process of claim 1 wherein the fiber is in fabric

1. A PROCESS FOR REDUCING THE PILLING TENDENCIES OF ACRYLIC FIBERS AND FIBER PRODUCTS THEREOF WHICH COMPRISES TREATING AN ACRYLIC FIBER OR PRODUCT THEREOF OBTAINED FROM AN ACRYLONITRILE POLYMER CONTAINING AT LEAST 80 WEIGHT PERCENT ACRYLONITRILE AND ANY BALANCE OF ONE OR MORE ETHYLENICALLY UNSATURATED MONOMERS COPOLYMERIZABLE THEREWITH WITH AN AQUEOUS SOLUTION CONTAINING A SALT OF AN ALKYLSULFATE OF 8 TO 16 CARBON ATOMS, SAID SALT SELECTED FROM SODIUM, POTASSIUM, AND AMMONIUM SALTS, AND SODIUM CARBONATE, SAID TREATMENT BEING CARRIED OUT AT A TEMPERATURE IN THE RANGE OF ABOUT 50* TO 100*C. AND SO AS TO DEPOSIT FROM 0.1 TO 2.0 WEIGHT PERCENT OF SAID ALKYLSULFATE AND FROM ABOUT 0.5 TO 3.0 WEIGHT PERCENT OF SODIUM CARBONATE, BOTH PERCENTAGES BASED ON THE DRY WEIGHT OF SAID FIBER OR FIBER PRODUCT, AND THEREAFTER DRYING THE TREATE FABRIC AT A TEMPERATURE IN THE RANGE OF ABOUT 60* TO 120*C.
 2. The process of claim 1 wherein the alkyl sulfate is sodium laurylsulfate.
 3. The process of claim 1 wherein the alkyl sulfate is deposited on said fiber or fiber Product at 0.1 to 1.0 weight percent.
 4. The process of claim 1 wherein the sodium carbonate is deposited on said fiber or fiber product at 0.5 to 2.0 weight percent.
 5. The process of claim 1 wherein the treated fabric is dried at 80*C.
 6. The process of claim 1 wherein the fiber or fiber product is treated at 60* to 80*C.
 7. The process of claim 1 wherein the fiber is in yarn form.
 8. The process of claim 1 wherein the fiber is in fabric form. 